RADIOSYNTHESIS OF METHYL AND HEPTYL [C-11] ISOCYANATES FROM [C-11] PHOSGENE, APPLICATION TO THE SYNTHESIS OF CARBAMATES - [C-11] PHYSOSTYGMINE AND [C-11] HEPTYLPHYSOSTIGMINE

[C-11]methylisocyanate and [C-11]heptylisocyanate were prepared within 10-11 min in amounts of 180-270 mCi (6.66-10 GBq) by action of [C-11]COCl2 on N,N-bis(trimethylsilyl)methylamine and heptylamine respectively. The characterization of the isocyanates was done by their reaction on eseroline which gives [C-11]physostigmine or [C-11]heptylphysostigmine (two inhibitors of acetylcholinesterase). [C-11]Isocyanates are obtained with a sp. act. of about 1.8 Ci/mu mol (66.6 GBq/mu mol), calculated for 10 min EOB which allows to synthesize 62-95 mCi (2.3-3.5 GBq) at 35 min EOB, of [C-11]physostigmine or [C-11]heptylphysostigmine, specific activity: 700-800 mCi/mu mol (25.9-39.6 GBq/mu mol). The interest in the use of amine or protected amine is discussed.